itemanalysis2: Classical Test Theory Item Analysis for Polytomous Items

Description

Classical Test Theory Item Analysis for Polytomous Items

Usage

itemanalysis2(data, options, ngroup = ncol(data) + 1, correction = TRUE,
span.par=.3,verbose=T)

Arguments

data

a data frame with N rows and m columns, with N denoting the number of subjects and m denoting the number of items.

options

a vector of numerical code of the response categories available for the items such as c(0,1,2,3). The minumum score is assumed to be 0.

ngroup

number of score groups to be use for plotting the item trace lines

correction

TRUE or FALSE. If it is TRUE, then an adjustment is made for point-biserial correlation.

span.par

a smoothing parameter to pass to ggplots when creating empirical ICCs

verbose

TRUE or FALSE. If it is TRUE, text output is printed.

Value

plots

a list object storing the item trace line plots for each item

item.stat

a matrix of basic item statistics

dist.sel

a matrix of distractor selection proportion statistics

dist.disc

a matrix of corrected point-biserial statistics for distractors

dist.disc

a matrix of corrected biserial statistics for distractors

Details

to be added later

Examples

Run this code

# NOT RUN {
 
# }
# NOT RUN {
    data(timss2011_usa)

    timss2011_usa$Q14B <- recode(var = timss2011_usa$Q14B,
                                 recodes = "c(0)=3;c(1)=2;c(2)=1;c(3)=0")

    timss2011_usa$Q14C <- recode(var = timss2011_usa$Q14C,
                                 recodes = "c(0)=3;c(1)=2;c(2)=1;c(3)=0")

    item.analysis <- itemanalysis2(data=timss2011_usa,
                                   options=c(0,1,2,3),
                                   ngroup=18,
                                   correction=FALSE)
                                   
    item.analysis$item.stat
      
    item.analysis$dist.sel
      
    item.analysis$dist.disc

    item.analysis$plots[[1]]   # Item Trace Line for the first item
    item.analysis$plots[[2]]   # Item Trace Line for the second item
    item.analysis$plots[[3]]   # Item Trace Line for the third item
    item.analysis$plots[[4]]   # Item Trace Line for the fourth item
    item.analysis$plots[[5]]   # Item Trace Line for the fifth item
    item.analysis$plots[[6]]   # Item Trace Line for the sixth item
  
# }